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Project 1 – Nanobiology and Nanomedicine
Simultaneous detection of C-reactive protein and other cardiac markers in human plasma using micromosaic immunoassays and self-regulating microfluidic networks
Marc Wolf, David Juncker, Bruno Michel, Patrick Hunziker, and Emmanuel Delamarche
Biosensors and Bioelectronics 19, (2004), 1193-1202
We show a proof-of-concept in which we combine our previously published concepts of micromosaic immunoassays (μMIAs) with self-regulating microfluidic networks (μFNs) to detect C-reactive protein (CRP) and other cardiac markers such as myoglobin (Mb) and cardiac Troponin I (cTnI). The μFNs are microfabricated in Si, have a well-defined surface chemistry, and are affixed to a bibulous material so as to self-regulate the displacement of an aliquot of liquid through the μFNs using capillary forces. An open section of the channels of the μFNs is covered with a hydrophobic ...
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Exploring amyloid formation by a de novo design
Richard A. Kammerer, Dirk Kostrewa, Jesús Zurdo, Andreas Detken, Carlos García-Echeverría, Janelle D. Green, Shirley A. Müller, Beat H. Meier, Fritz K. Winkler, Christopher M. Dobson and Michel O. Steinmetz
Proc. Nat. Acad. Sci. 101 (2004), 4435-4440
Protein deposition as amyloid fibrils underlies many debilitating human disorders. The complexity and size of disease-related polypeptides, however, often hinders a detailed rational approach to study effects that contribute to the process of amyloid formation. We report here a simplified peptide sequence successfully designed de novo to fold into a coiled-coil conformation under ambient conditions but to transform into amyloid fibrils at elevated temperatures. We have determined the crystal structure of the coiled-coil form and propose a detailed molecular model for the peptide in its fibrill ...
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Human Amylin Oligomer Growth and Fibril Elongation Define Two Distinct Phases in Amyloid Formation
Janelle D. Green, Claire Goldsbury, Joerg Kistler, Garth J. S. Cooper, and Ueli Aebi
J. Biol. Chem. 279 (2004), 12206-12212
Human amylin (hA), a 37-amino-acid polypeptide, is one of a number of peptides with the ability to form amyloid fibrils and cause disease. It is the main constituent of the pancreatic amyloid deposits associated with type 2 diabetes. Increasing interest in early assembly intermediates rather than the mature fibrils as the cytotoxic agent has led to this study in which the smallest hA oligomers have been captured by atomic force microscopy. These are 2.3 ± 1.9 nm in height, 23 ± 14 nm in length, and consist of an estimated 16 hA molecules. Oligomers first grow to a height of about 6 nm before t ...
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Assessing the Flexibility of Intermediate Filaments by Atomic Force Microscopy
N. Mücke, L. Kreplak, R. Kirmse, T. Wedig, H. Herrmann, U. Aebi and J. Langowski
J. Mol. Biol. 335 (2004) 1241-1250
Eukaryotic cells contain three cytoskeletal filament systems that exhibit very distinct assembly properties, supramolecular architectures, dynamic behaviour and mechanical properties. Microtubules and microfilaments are relatively stiff polar structures whose assembly is modulated by the state of hydrolysis of the bound nucleotide. In contrast, intermediate filaments (IFs) are more flexible apolar structures assembled from a ~45 nm long coiled-coil dimer as the elementary building block. The differences in flexibility that exist among the three filament systems have been described qualitativel ...
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Dynamic Elastic Modulus of Porcine Articular Cartilage Determined at Two Different Levels of Tissue Organization by Indentation-Type Atomic Force Microscopy
Martin Stolz, Roberto Raiteri , A. U. Daniels , Mark R. VanLandingham , Werner Baschong and Ueli Aebi
Biophys. J. 86, 3269-3283 (2004)
Cartilage stiffness was measured ex vivo at the micrometer and nanometer scales to explore structure-mechanical property relationships at smaller scales than has been done previously. A method was developed to measure the dynamic elastic modulus, |E*|, in compression by indentation-type atomic force microscopy (IT AFM). Spherical indenter tips (radius = 2.5 µm) and sharp pyramidal tips (radius = 20 nm) were employed to probe micrometer-scale and nanometer-scale response, respectively. |E*| values were obtained at 3 Hz from 1024 unloading response curves recorded at a given location on subsurfa ...
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Structural Analysis of the Reaction Center Light-harvesting Complex I Photosynthetic Core Complex of Rhodospirillum rubrum Using Atomic Force Microscopy
Dimitrios Fotiadis, Pu Qian, Ansgar Philippsen, Per A. Bullough, Andreas Engel, and C. Neil Hunter|
J. Biol. Chem., Vol. 279, Issue 3, 2063-2068, January 16, 2004
The bacterium Rhodospirillum rubrum contains a simple photosynthetic system, in which the reaction center (RC) receives energy from the light-harvesting (LH1) complex. We have used high-resolution atomic force microscopy (AFM) to image two-dimensional crystals of the RC-LH1 complex of R. rubrum. The AFM topographs show that the RC-LH1 complex is 94 Å in height, the RC-H subunit protrudes from the cytoplasmic face of the membrane by 40 Å, and it sits 21 Å above the highest point of the surrounding LH1 ring. In contrast, the RC on the periplasmic side is at a lower level than LH1, which protrude ...
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Development of Insulated Conductive Probes with Platinum Silicide Tips for Atomic Force Microscopy in Cell Biology
Terunobu Akiyama, Maurizio R. Gullo, Nicolaas F. de Rooij, Andreas Tonin, Hans-Rudolf Hidber, Patrick L. T. M. Frederix, Andreas Engel and Urs Staufer
Japanese Journal of Applied Physics 43, 3865-3867 (2004)
A microfabrication process of a multifunctional probe is introduced for atomic force microscopy and various electrochemical measurements on biological samples in buffer solution. The silicon nitride probes have a spring constant lower than 0.1 N/m and a conductive tip, which is tightly insulated except at the apex. The conductive core of the tip consists of PtxSiy and shows a typical radius of curvature of 15 nm. A simultaneous measurement of topography and electrical current on graphite in air was demonstrated.
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Molecular architecture of photosynthetic membranes in Rhodobacter sphaeroides: the role of PufX
C Alistair Siebert, Pu Qian, Dimitrios Fotiadis, Andreas Engel, C Neil Hunter and Per A Bullough
The EMBO Journal, Vol. 23, No. 4 pp. 690-700, 2004
The effects of the PufX polypeptide on membrane architecture were investigated by comparing the composition and structures of photosynthetic membranes from PufX+ and PufX- strains of Rhodobacter sphaeroides. We show that this single polypeptide profoundly affects membrane morphology, leading to highly elongated cells containing extended tubular membranes. Purified tubular membranes contain helical arrays composed solely of dimeric RC–LH1–PufX (RC, reaction centre; LH, light harvesting) complexes with apparently open LH1 rings. PufX- cells contain crystalline membranes with a pseudo-hexagonal p ...
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Carbohydrate–carbohydrate interaction provides adhesion force and specificity for cellular recognition
Iwona Bucior, Simon Scheuring, Andreas Engel, and Max M. Burger
J Cell Biol 165, 529-537 (2004)
The adhesion force and specificity in the first experimental evidence for cell–cell recognition in the animal kingdom were assigned to marine sponge cell surface proteoglycans. However, the question whether the specificity resided in a protein or carbohydrate moiety could not yet be resolved. Here, the strength and species specificity of cell–cell recognition could be assigned to a direct carbohydrate–carbohydrate interaction. Atomic force microscopy measurements revealed equally strong adhesion forces between glycan molecules (190–310 piconewtons) as between proteins in antibody–antigen inter ...
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Rapid functionalization of cantilever array sensors by inkjet printing
Alexander Bietsch, Jiayun Zhang, Martin Hegner, Hans Peter Lang and Christoph Gerber
Nanotechnology 15, 873-880 (2004)
The controlled deposition of functional layers is the key to converting nanomechanical cantilevers into chemical or biochemical sensors. Here, we introduce inkjet printing as a rapid and general method to coat cantilever arrays efficiently with various sensor layers. Self-assembled monolayers of alkanethiols were deposited on selected Au-coated cantilevers and rendered them sensitive to ion concentrations or pH in liquids. The detection of gene fragments was achieved with cantilever sensors coated with thiol-linked single-stranded DNA oligomers on Au. A selective etch protocol proved the unifo ...
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Inkjet Deposition of Alkanethiolate Monolayers and DNA Oligonucleotides on Gold: Evaluation of Spot Uniformity by Wet Etching
Alexander Bietsch, Martin Hegner, Hans Peter Lang, and Christoph Gerber
Langmuir, 20 (12), 5119 -5122, 2004
Inkjet printing allows localized, contact-free deposition of liquids onto arbitrary substrates. In this article we demonstrate the fast formation of high-quality self-assembled monolayers (SAMs) on gold surfaces. Using a selective etch process, we verify the uniformity of the deposited spots. A direct comparison with microcontact-printed SAMs on Au revealed similar resist quality as inkjet-deposited alkanethiolate SAMs. Likewise, inkjet printing of thiol-functionalized and non-thiolated single-stranded DNA oligomers formed molecular layers protecting Au from etchants. For all compounds used, w ...
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Atomic Force Microscopy & Laser Tweezers, Vol 19. (2004)
Engel A, Hegner M, Edited by Gompper G, Kaupp, U.B., Dhont, J.K.G., Richter, D. Winkler,
R.G. Jülich: Forschungszentrum Jülich; 2004.
High resolution imaging of bacteriorhodopsin by atomic force microscopy:
Methods and protocols in biomedical applications
Fotiadis D, Engel A, Edited by Braga PC, Ricci D: Humana Press Inc.;
Methods in Molecular Medicine 2004: 291-303.
Full list of publications
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